The long-term objectives are to study adhesive mechanisms involving two surface glycoproteins during development and regeneration of ischiatic nerves. Experiments will focus on Schwann cell--neuron interactions that are mediated by N-CAM and Ng-CAM. The specific aims include: 1) Localize cell adhesion molecules in developing and adult nerves and describe changes in CAM distribution that are induced by injury and regeneration. Immunohistological techniques will be used to localize CAMs in the light and electron microscope. Computer-generated 3-dimensional reconstructions and morphometric analyses of CAM distributions will be produced. 2) Test the role of CAMs in regeneration by perturbing their function in vivo. Prosthetic tubes containing antibodies to the molecules will be attached to severed nerves and perturbations will be assayed immunohistologically, biochemically and behaviorally. 3) Quantitate changes in the synthesis and transport of CAMs that are induced by injury and describe their contributions to regeneration. Biochemical assays will measure the amounts and forms of the molecules synthesized and secreted by cells in culture. The extent to which extracellular CAMs alter Schwann cell migration in a chemotaxis chamber on proliferation in vitro will be assayed. 4) Test the roles of identified CAMs in Schwann cell adhesion and ensheathment of axons; search for new molecules that may be involved. Antibody perturbation will be used to block adhesion of Schwann cells to Schwann cells, neurons, extracellular matrix, and axolemmal or myelin components in vitro. Monoclonal antibodies will be produced against uncharacterized substances that are isolated from regenerating nerves. Antigens will then be partially characterized. 5) Manipulate the environment of the injured nerve to enhance regeneration. Substances will be screened for their ability to increase the speed and extent of target reinnervation by including them in prosthetic tubes attached to transected nerves. Immunohistological, biochemical, and behavioral assays will be quantitate the extent of reinnervation. The results should provide a more complete description of cellular interactions during regeneration than currently exists and should suggest approaches to increase the efficacy of regeneration through prosthetic implants.